includes/libs/rdbms/database/IDatabase.php

   1 <?php
   2
   3 /**
   4  * @defgroup Database Database
   5  *
   6  * This file deals with database interface functions
   7  * and query specifics/optimisations.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  * @ingroup Database
  26  */
  27
  28 /**
  29  * Basic database interface for live and lazy-loaded relation database handles
  30  *
  31  * @note: IDatabase and DBConnRef should be updated to reflect any changes
  32  * @ingroup Database
  33  */
  34 interface IDatabase {
  35         /** @var int Callback triggered immediately due to no active transaction */
  36         const TRIGGER_IDLE = 1;
  37         /** @var int Callback triggered by COMMIT */
  38         const TRIGGER_COMMIT = 2;
  39         /** @var int Callback triggered by ROLLBACK */
  40         const TRIGGER_ROLLBACK = 3;
  41
  42         /** @var string Transaction is requested by regular caller outside of the DB layer */
  43         const TRANSACTION_EXPLICIT = '';
  44         /** @var string Transaction is requested internally via DBO_TRX/startAtomic() */
  45         const TRANSACTION_INTERNAL = 'implicit';
  46
  47         /** @var string Transaction operation comes from service managing all DBs */
  48         const FLUSHING_ALL_PEERS = 'flush';
  49         /** @var string Transaction operation comes from the database class internally */
  50         const FLUSHING_INTERNAL = 'flush';
  51
  52         /** @var string Do not remember the prior flags */
  53         const REMEMBER_NOTHING = '';
  54         /** @var string Remember the prior flags */
  55         const REMEMBER_PRIOR = 'remember';
  56         /** @var string Restore to the prior flag state */
  57         const RESTORE_PRIOR = 'prior';
  58         /** @var string Restore to the initial flag state */
  59         const RESTORE_INITIAL = 'initial';
  60
  61         /** @var string Estimate total time (RTT, scanning, waiting on locks, applying) */
  62         const ESTIMATE_TOTAL = 'total';
  63         /** @var string Estimate time to apply (scanning, applying) */
  64         const ESTIMATE_DB_APPLY = 'apply';
  65
  66         /** @var int Combine list with comma delimeters */
  67         const LIST_COMMA = 0;
  68         /** @var int Combine list with AND clauses */
  69         const LIST_AND = 1;
  70         /** @var int Convert map into a SET clause */
  71         const LIST_SET = 2;
  72         /** @var int Treat as field name and do not apply value escaping */
  73         const LIST_NAMES = 3;
  74         /** @var int Combine list with OR clauses */
  75         const LIST_OR = 4;
  76
  77         /**
  78          * A string describing the current software version, and possibly
  79          * other details in a user-friendly way. Will be listed on Special:Version, etc.
  80          * Use getServerVersion() to get machine-friendly information.
  81          *
  82          * @return string Version information from the database server
  83          */
  84         public function getServerInfo();
  85
  86         /**
  87          * Turns buffering of SQL result sets on (true) or off (false). Default is "on".
  88          *
  89          * Unbuffered queries are very troublesome in MySQL:
  90          *
  91          *   - If another query is executed while the first query is being read
  92          *     out, the first query is killed. This means you can't call normal
  93          *     Database functions while you are reading an unbuffered query result
  94          *     from a normal Database connection.
  95          *
  96          *   - Unbuffered queries cause the MySQL server to use large amounts of
  97          *     memory and to hold broad locks which block other queries.
  98          *
  99          * If you want to limit client-side memory, it's almost always better to
 100          * split up queries into batches using a LIMIT clause than to switch off
 101          * buffering.
 102          *
 103          * @param null|bool $buffer
 104          * @return null|bool The previous value of the flag
 105          */
 106         public function bufferResults( $buffer = null );
 107
 108         /**
 109          * Gets the current transaction level.
 110          *
 111          * Historically, transactions were allowed to be "nested". This is no
 112          * longer supported, so this function really only returns a boolean.
 113          *
 114          * @return int The previous value
 115          */
 116         public function trxLevel();
 117
 118         /**
 119          * Get the UNIX timestamp of the time that the transaction was established
 120          *
 121          * This can be used to reason about the staleness of SELECT data
 122          * in REPEATABLE-READ transaction isolation level.
 123          *
 124          * @return float|null Returns null if there is not active transaction
 125          * @since 1.25
 126          */
 127         public function trxTimestamp();
 128
 129         /**
 130          * @return bool Whether an explicit transaction or atomic sections are still open
 131          * @since 1.28
 132          */
 133         public function explicitTrxActive();
 134
 135         /**
 136          * Get/set the table prefix.
 137          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 138          * @return string The previous table prefix.
 139          */
 140         public function tablePrefix( $prefix = null );
 141
 142         /**
 143          * Get/set the db schema.
 144          * @param string $schema The database schema to set, or omitted to leave it unchanged.
 145          * @return string The previous db schema.
 146          */
 147         public function dbSchema( $schema = null );
 148
 149         /**
 150          * Get properties passed down from the server info array of the load
 151          * balancer.
 152          *
 153          * @param string $name The entry of the info array to get, or null to get the
 154          *   whole array
 155          *
 156          * @return array|mixed|null
 157          */
 158         public function getLBInfo( $name = null );
 159
 160         /**
 161          * Set the LB info array, or a member of it. If called with one parameter,
 162          * the LB info array is set to that parameter. If it is called with two
 163          * parameters, the member with the given name is set to the given value.
 164          *
 165          * @param string $name
 166          * @param array $value
 167          */
 168         public function setLBInfo( $name, $value = null );
 169
 170         /**
 171          * Set a lazy-connecting DB handle to the master DB (for replication status purposes)
 172          *
 173          * @param IDatabase $conn
 174          * @since 1.27
 175          */
 176         public function setLazyMasterHandle( IDatabase $conn );
 177
 178         /**
 179          * Returns true if this database does an implicit sort when doing GROUP BY
 180          *
 181          * @return bool
 182          */
 183         public function implicitGroupby();
 184
 185         /**
 186          * Returns true if this database does an implicit order by when the column has an index
 187          * For example: SELECT page_title FROM page LIMIT 1
 188          *
 189          * @return bool
 190          */
 191         public function implicitOrderby();
 192
 193         /**
 194          * Return the last query that went through IDatabase::query()
 195          * @return string
 196          */
 197         public function lastQuery();
 198
 199         /**
 200          * Returns true if the connection may have been used for write queries.
 201          * Should return true if unsure.
 202          *
 203          * @return bool
 204          */
 205         public function doneWrites();
 206
 207         /**
 208          * Returns the last time the connection may have been used for write queries.
 209          * Should return a timestamp if unsure.
 210          *
 211          * @return int|float UNIX timestamp or false
 212          * @since 1.24
 213          */
 214         public function lastDoneWrites();
 215
 216         /**
 217          * @return bool Whether there is a transaction open with possible write queries
 218          * @since 1.27
 219          */
 220         public function writesPending();
 221
 222         /**
 223          * Returns true if there is a transaction open with possible write
 224          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 225          * This does *not* count recurring callbacks, e.g. from setTransactionListener().
 226          *
 227          * @return bool
 228          */
 229         public function writesOrCallbacksPending();
 230
 231         /**
 232          * Get the time spend running write queries for this transaction
 233          *
 234          * High times could be due to scanning, updates, locking, and such
 235          *
 236          * @param string $type IDatabase::ESTIMATE_* constant [default: ESTIMATE_ALL]
 237          * @return float|bool Returns false if not transaction is active
 238          * @since 1.26
 239          */
 240         public function pendingWriteQueryDuration( $type = self::ESTIMATE_TOTAL );
 241
 242         /**
 243          * Get the list of method names that did write queries for this transaction
 244          *
 245          * @return array
 246          * @since 1.27
 247          */
 248         public function pendingWriteCallers();
 249
 250         /**
 251          * Is a connection to the database open?
 252          * @return bool
 253          */
 254         public function isOpen();
 255
 256         /**
 257          * Set a flag for this connection
 258          *
 259          * @param int $flag DBO_* constants from Defines.php:
 260          *   - DBO_DEBUG: output some debug info (same as debug())
 261          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 262          *   - DBO_TRX: automatically start transactions
 263          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 264          *       and removes it in command line mode
 265          *   - DBO_PERSISTENT: use persistant database connection
 266          * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
 267          */
 268         public function setFlag( $flag, $remember = self::REMEMBER_NOTHING );
 269
 270         /**
 271          * Clear a flag for this connection
 272          *
 273          * @param int $flag DBO_* constants from Defines.php:
 274          *   - DBO_DEBUG: output some debug info (same as debug())
 275          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 276          *   - DBO_TRX: automatically start transactions
 277          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 278          *       and removes it in command line mode
 279          *   - DBO_PERSISTENT: use persistant database connection
 280          * @param string $remember IDatabase::REMEMBER_* constant [default: REMEMBER_NOTHING]
 281          */
 282         public function clearFlag( $flag, $remember = self::REMEMBER_NOTHING );
 283
 284         /**
 285          * Restore the flags to their prior state before the last setFlag/clearFlag call
 286          *
 287          * @param string $state IDatabase::RESTORE_* constant. [default: RESTORE_PRIOR]
 288          * @since 1.28
 289          */
 290         public function restoreFlags( $state = self::RESTORE_PRIOR );
 291
 292         /**
 293          * Returns a boolean whether the flag $flag is set for this connection
 294          *
 295          * @param int $flag DBO_* constants from Defines.php:
 296          *   - DBO_DEBUG: output some debug info (same as debug())
 297          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 298          *   - DBO_TRX: automatically start transactions
 299          *   - DBO_PERSISTENT: use persistant database connection
 300          * @return bool
 301          */
 302         public function getFlag( $flag );
 303
 304         /**
 305          * General read-only accessor
 306          *
 307          * @param string $name
 308          * @return string
 309          */
 310         public function getProperty( $name );
 311
 312         /**
 313          * @return string
 314          */
 315         public function getDomainID();
 316
 317         /**
 318          * Alias for getDomainID()
 319          *
 320          * @return string
 321          */
 322         public function getWikiID();
 323
 324         /**
 325          * Get the type of the DBMS, as it appears in $wgDBtype.
 326          *
 327          * @return string
 328          */
 329         public function getType();
 330
 331         /**
 332          * Open a connection to the database. Usually aborts on failure
 333          *
 334          * @param string $server Database server host
 335          * @param string $user Database user name
 336          * @param string $password Database user password
 337          * @param string $dbName Database name
 338          * @return bool
 339          * @throws DBConnectionError
 340          */
 341         public function open( $server, $user, $password, $dbName );
 342
 343         /**
 344          * Fetch the next row from the given result object, in object form.
 345          * Fields can be retrieved with $row->fieldname, with fields acting like
 346          * member variables.
 347          * If no more rows are available, false is returned.
 348          *
 349          * @param ResultWrapper|stdClass $res Object as returned from IDatabase::query(), etc.
 350          * @return stdClass|bool
 351          * @throws DBUnexpectedError Thrown if the database returns an error
 352          */
 353         public function fetchObject( $res );
 354
 355         /**
 356          * Fetch the next row from the given result object, in associative array
 357          * form. Fields are retrieved with $row['fieldname'].
 358          * If no more rows are available, false is returned.
 359          *
 360          * @param ResultWrapper $res Result object as returned from IDatabase::query(), etc.
 361          * @return array|bool
 362          * @throws DBUnexpectedError Thrown if the database returns an error
 363          */
 364         public function fetchRow( $res );
 365
 366         /**
 367          * Get the number of rows in a result object
 368          *
 369          * @param mixed $res A SQL result
 370          * @return int
 371          */
 372         public function numRows( $res );
 373
 374         /**
 375          * Get the number of fields in a result object
 376          * @see http://www.php.net/mysql_num_fields
 377          *
 378          * @param mixed $res A SQL result
 379          * @return int
 380          */
 381         public function numFields( $res );
 382
 383         /**
 384          * Get a field name in a result object
 385          * @see http://www.php.net/mysql_field_name
 386          *
 387          * @param mixed $res A SQL result
 388          * @param int $n
 389          * @return string
 390          */
 391         public function fieldName( $res, $n );
 392
 393         /**
 394          * Get the inserted value of an auto-increment row
 395          *
 396          * The value inserted should be fetched from nextSequenceValue()
 397          *
 398          * Example:
 399          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 400          * $dbw->insert( 'page', [ 'page_id' => $id ] );
 401          * $id = $dbw->insertId();
 402          *
 403          * @return int
 404          */
 405         public function insertId();
 406
 407         /**
 408          * Change the position of the cursor in a result object
 409          * @see http://www.php.net/mysql_data_seek
 410          *
 411          * @param mixed $res A SQL result
 412          * @param int $row
 413          */
 414         public function dataSeek( $res, $row );
 415
 416         /**
 417          * Get the last error number
 418          * @see http://www.php.net/mysql_errno
 419          *
 420          * @return int
 421          */
 422         public function lastErrno();
 423
 424         /**
 425          * Get a description of the last error
 426          * @see http://www.php.net/mysql_error
 427          *
 428          * @return string
 429          */
 430         public function lastError();
 431
 432         /**
 433          * mysql_fetch_field() wrapper
 434          * Returns false if the field doesn't exist
 435          *
 436          * @param string $table Table name
 437          * @param string $field Field name
 438          *
 439          * @return Field
 440          */
 441         public function fieldInfo( $table, $field );
 442
 443         /**
 444          * Get the number of rows affected by the last write query
 445          * @see http://www.php.net/mysql_affected_rows
 446          *
 447          * @return int
 448          */
 449         public function affectedRows();
 450
 451         /**
 452          * Returns a wikitext link to the DB's website, e.g.,
 453          *   return "[http://www.mysql.com/ MySQL]";
 454          * Should at least contain plain text, if for some reason
 455          * your database has no website.
 456          *
 457          * @return string Wikitext of a link to the server software's web site
 458          */
 459         public function getSoftwareLink();
 460
 461         /**
 462          * A string describing the current software version, like from
 463          * mysql_get_server_info().
 464          *
 465          * @return string Version information from the database server.
 466          */
 467         public function getServerVersion();
 468
 469         /**
 470          * Closes a database connection.
 471          * if it is open : commits any open transactions
 472          *
 473          * @throws DBError
 474          * @return bool Operation success. true if already closed.
 475          */
 476         public function close();
 477
 478         /**
 479          * @param string $error Fallback error message, used if none is given by DB
 480          * @throws DBConnectionError
 481          */
 482         public function reportConnectionError( $error = 'Unknown error' );
 483
 484         /**
 485          * Run an SQL query and return the result. Normally throws a DBQueryError
 486          * on failure. If errors are ignored, returns false instead.
 487          *
 488          * In new code, the query wrappers select(), insert(), update(), delete(),
 489          * etc. should be used where possible, since they give much better DBMS
 490          * independence and automatically quote or validate user input in a variety
 491          * of contexts. This function is generally only useful for queries which are
 492          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 493          * as CREATE TABLE.
 494          *
 495          * However, the query wrappers themselves should call this function.
 496          *
 497          * @param string $sql SQL query
 498          * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
 499          *     comment (you can use __METHOD__ or add some extra info)
 500          * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
 501          *     maybe best to catch the exception instead?
 502          * @throws DBError
 503          * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
 504          *     for a successful read query, or false on failure if $tempIgnore set
 505          */
 506         public function query( $sql, $fname = __METHOD__, $tempIgnore = false );
 507
 508         /**
 509          * Report a query error. Log the error, and if neither the object ignore
 510          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 511          *
 512          * @param string $error
 513          * @param int $errno
 514          * @param string $sql
 515          * @param string $fname
 516          * @param bool $tempIgnore
 517          * @throws DBQueryError
 518          */
 519         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
 520
 521         /**
 522          * Free a result object returned by query() or select(). It's usually not
 523          * necessary to call this, just use unset() or let the variable holding
 524          * the result object go out of scope.
 525          *
 526          * @param mixed $res A SQL result
 527          */
 528         public function freeResult( $res );
 529
 530         /**
 531          * A SELECT wrapper which returns a single field from a single result row.
 532          *
 533          * Usually throws a DBQueryError on failure. If errors are explicitly
 534          * ignored, returns false on failure.
 535          *
 536          * If no result rows are returned from the query, false is returned.
 537          *
 538          * @param string|array $table Table name. See IDatabase::select() for details.
 539          * @param string $var The field name to select. This must be a valid SQL
 540          *   fragment: do not use unvalidated user input.
 541          * @param string|array $cond The condition array. See IDatabase::select() for details.
 542          * @param string $fname The function name of the caller.
 543          * @param string|array $options The query options. See IDatabase::select() for details.
 544          *
 545          * @return bool|mixed The value from the field, or false on failure.
 546          */
 547         public function selectField(
 548                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
 549         );
 550
 551         /**
 552          * A SELECT wrapper which returns a list of single field values from result rows.
 553          *
 554          * Usually throws a DBQueryError on failure. If errors are explicitly
 555          * ignored, returns false on failure.
 556          *
 557          * If no result rows are returned from the query, false is returned.
 558          *
 559          * @param string|array $table Table name. See IDatabase::select() for details.
 560          * @param string $var The field name to select. This must be a valid SQL
 561          *   fragment: do not use unvalidated user input.
 562          * @param string|array $cond The condition array. See IDatabase::select() for details.
 563          * @param string $fname The function name of the caller.
 564          * @param string|array $options The query options. See IDatabase::select() for details.
 565          *
 566          * @return bool|array The values from the field, or false on failure
 567          * @since 1.25
 568          */
 569         public function selectFieldValues(
 570                 $table, $var, $cond = '', $fname = __METHOD__, $options = []
 571         );
 572
 573         /**
 574          * Execute a SELECT query constructed using the various parameters provided.
 575          * See below for full details of the parameters.
 576          *
 577          * @param string|array $table Table name
 578          * @param string|array $vars Field names
 579          * @param string|array $conds Conditions
 580          * @param string $fname Caller function name
 581          * @param array $options Query options
 582          * @param array $join_conds Join conditions
 583          *
 584          *
 585          * @param string|array $table
 586          *
 587          * May be either an array of table names, or a single string holding a table
 588          * name. If an array is given, table aliases can be specified, for example:
 589          *
 590          *    [ 'a' => 'user' ]
 591          *
 592          * This includes the user table in the query, with the alias "a" available
 593          * for use in field names (e.g. a.user_name).
 594          *
 595          * All of the table names given here are automatically run through
 596          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
 597          * added, and various other table name mappings to be performed.
 598          *
 599          * Do not use untrusted user input as a table name. Alias names should
 600          * not have characters outside of the Basic multilingual plane.
 601          *
 602          * @param string|array $vars
 603          *
 604          * May be either a field name or an array of field names. The field names
 605          * can be complete fragments of SQL, for direct inclusion into the SELECT
 606          * query. If an array is given, field aliases can be specified, for example:
 607          *
 608          *   [ 'maxrev' => 'MAX(rev_id)' ]
 609          *
 610          * This includes an expression with the alias "maxrev" in the query.
 611          *
 612          * If an expression is given, care must be taken to ensure that it is
 613          * DBMS-independent.
 614          *
 615          * Untrusted user input must not be passed to this parameter.
 616          *
 617          * @param string|array $conds
 618          *
 619          * May be either a string containing a single condition, or an array of
 620          * conditions. If an array is given, the conditions constructed from each
 621          * element are combined with AND.
 622          *
 623          * Array elements may take one of two forms:
 624          *
 625          *   - Elements with a numeric key are interpreted as raw SQL fragments.
 626          *   - Elements with a string key are interpreted as equality conditions,
 627          *     where the key is the field name.
 628          *     - If the value of such an array element is a scalar (such as a
 629          *       string), it will be treated as data and thus quoted appropriately.
 630          *       If it is null, an IS NULL clause will be added.
 631          *     - If the value is an array, an IN (...) clause will be constructed
 632          *       from its non-null elements, and an IS NULL clause will be added
 633          *       if null is present, such that the field may match any of the
 634          *       elements in the array. The non-null elements will be quoted.
 635          *
 636          * Note that expressions are often DBMS-dependent in their syntax.
 637          * DBMS-independent wrappers are provided for constructing several types of
 638          * expression commonly used in condition queries. See:
 639          *    - IDatabase::buildLike()
 640          *    - IDatabase::conditional()
 641          *
 642          * Untrusted user input is safe in the values of string keys, however untrusted
 643          * input must not be used in the array key names or in the values of numeric keys.
 644          * Escaping of untrusted input used in values of numeric keys should be done via
 645          * IDatabase::addQuotes()
 646          *
 647          * @param string|array $options
 648          *
 649          * Optional: Array of query options. Boolean options are specified by
 650          * including them in the array as a string value with a numeric key, for
 651          * example:
 652          *
 653          *    [ 'FOR UPDATE' ]
 654          *
 655          * The supported options are:
 656          *
 657          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
 658          *     with LIMIT can theoretically be used for paging through a result set,
 659          *     but this is discouraged for performance reasons.
 660          *
 661          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
 662          *     and then the first rows are taken until the limit is reached. LIMIT
 663          *     is applied to a result set after OFFSET.
 664          *
 665          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
 666          *     changed until the next COMMIT.
 667          *
 668          *   - DISTINCT: Boolean: return only unique result rows.
 669          *
 670          *   - GROUP BY: May be either an SQL fragment string naming a field or
 671          *     expression to group by, or an array of such SQL fragments.
 672          *
 673          *   - HAVING: May be either an string containing a HAVING clause or an array of
 674          *     conditions building the HAVING clause. If an array is given, the conditions
 675          *     constructed from each element are combined with AND.
 676          *
 677          *   - ORDER BY: May be either an SQL fragment giving a field name or
 678          *     expression to order by, or an array of such SQL fragments.
 679          *
 680          *   - USE INDEX: This may be either a string giving the index name to use
 681          *     for the query, or an array. If it is an associative array, each key
 682          *     gives the table name (or alias), each value gives the index name to
 683          *     use for that table. All strings are SQL fragments and so should be
 684          *     validated by the caller.
 685          *
 686          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
 687          *     instead of SELECT.
 688          *
 689          * And also the following boolean MySQL extensions, see the MySQL manual
 690          * for documentation:
 691          *
 692          *    - LOCK IN SHARE MODE
 693          *    - STRAIGHT_JOIN
 694          *    - HIGH_PRIORITY
 695          *    - SQL_BIG_RESULT
 696          *    - SQL_BUFFER_RESULT
 697          *    - SQL_SMALL_RESULT
 698          *    - SQL_CALC_FOUND_ROWS
 699          *    - SQL_CACHE
 700          *    - SQL_NO_CACHE
 701          *
 702          *
 703          * @param string|array $join_conds
 704          *
 705          * Optional associative array of table-specific join conditions. In the
 706          * most common case, this is unnecessary, since the join condition can be
 707          * in $conds. However, it is useful for doing a LEFT JOIN.
 708          *
 709          * The key of the array contains the table name or alias. The value is an
 710          * array with two elements, numbered 0 and 1. The first gives the type of
 711          * join, the second is the same as the $conds parameter. Thus it can be
 712          * an SQL fragment, or an array where the string keys are equality and the
 713          * numeric keys are SQL fragments all AND'd together. For example:
 714          *
 715          *    [ 'page' => [ 'LEFT JOIN', 'page_latest=rev_id' ] ]
 716          *
 717          * @return ResultWrapper|bool If the query returned no rows, a ResultWrapper
 718          *   with no rows in it will be returned. If there was a query error, a
 719          *   DBQueryError exception will be thrown, except if the "ignore errors"
 720          *   option was set, in which case false will be returned.
 721          */
 722         public function select(
 723                 $table, $vars, $conds = '', $fname = __METHOD__,
 724                 $options = [], $join_conds = []
 725         );
 726
 727         /**
 728          * The equivalent of IDatabase::select() except that the constructed SQL
 729          * is returned, instead of being immediately executed. This can be useful for
 730          * doing UNION queries, where the SQL text of each query is needed. In general,
 731          * however, callers outside of Database classes should just use select().
 732          *
 733          * @param string|array $table Table name
 734          * @param string|array $vars Field names
 735          * @param string|array $conds Conditions
 736          * @param string $fname Caller function name
 737          * @param string|array $options Query options
 738          * @param string|array $join_conds Join conditions
 739          *
 740          * @return string SQL query string.
 741          * @see IDatabase::select()
 742          */
 743         public function selectSQLText(
 744                 $table, $vars, $conds = '', $fname = __METHOD__,
 745                 $options = [], $join_conds = []
 746         );
 747
 748         /**
 749          * Single row SELECT wrapper. Equivalent to IDatabase::select(), except
 750          * that a single row object is returned. If the query returns no rows,
 751          * false is returned.
 752          *
 753          * @param string|array $table Table name
 754          * @param string|array $vars Field names
 755          * @param array $conds Conditions
 756          * @param string $fname Caller function name
 757          * @param string|array $options Query options
 758          * @param array|string $join_conds Join conditions
 759          *
 760          * @return stdClass|bool
 761          */
 762         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
 763                 $options = [], $join_conds = []
 764         );
 765
 766         /**
 767          * Estimate the number of rows in dataset
 768          *
 769          * MySQL allows you to estimate the number of rows that would be returned
 770          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
 771          * index cardinality statistics, and is notoriously inaccurate, especially
 772          * when large numbers of rows have recently been added or deleted.
 773          *
 774          * For DBMSs that don't support fast result size estimation, this function
 775          * will actually perform the SELECT COUNT(*).
 776          *
 777          * Takes the same arguments as IDatabase::select().
 778          *
 779          * @param string $table Table name
 780          * @param string $vars Unused
 781          * @param array|string $conds Filters on the table
 782          * @param string $fname Function name for profiling
 783          * @param array $options Options for select
 784          * @return int Row count
 785          */
 786         public function estimateRowCount(
 787                 $table, $vars = '*', $conds = '', $fname = __METHOD__, $options = []
 788         );
 789
 790         /**
 791          * Get the number of rows in dataset
 792          *
 793          * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
 794          *
 795          * Takes the same arguments as IDatabase::select().
 796          *
 797          * @since 1.27 Added $join_conds parameter
 798          *
 799          * @param array|string $tables Table names
 800          * @param string $vars Unused
 801          * @param array|string $conds Filters on the table
 802          * @param string $fname Function name for profiling
 803          * @param array $options Options for select
 804          * @param array $join_conds Join conditions (since 1.27)
 805          * @return int Row count
 806          */
 807         public function selectRowCount(
 808                 $tables, $vars = '*', $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 809         );
 810
 811         /**
 812          * Determines whether a field exists in a table
 813          *
 814          * @param string $table Table name
 815          * @param string $field Filed to check on that table
 816          * @param string $fname Calling function name (optional)
 817          * @return bool Whether $table has filed $field
 818          */
 819         public function fieldExists( $table, $field, $fname = __METHOD__ );
 820
 821         /**
 822          * Determines whether an index exists
 823          * Usually throws a DBQueryError on failure
 824          * If errors are explicitly ignored, returns NULL on failure
 825          *
 826          * @param string $table
 827          * @param string $index
 828          * @param string $fname
 829          * @return bool|null
 830          */
 831         public function indexExists( $table, $index, $fname = __METHOD__ );
 832
 833         /**
 834          * Query whether a given table exists
 835          *
 836          * @param string $table
 837          * @param string $fname
 838          * @return bool
 839          */
 840         public function tableExists( $table, $fname = __METHOD__ );
 841
 842         /**
 843          * Determines if a given index is unique
 844          *
 845          * @param string $table
 846          * @param string $index
 847          *
 848          * @return bool
 849          */
 850         public function indexUnique( $table, $index );
 851
 852         /**
 853          * INSERT wrapper, inserts an array into a table.
 854          *
 855          * $a may be either:
 856          *
 857          *   - A single associative array. The array keys are the field names, and
 858          *     the values are the values to insert. The values are treated as data
 859          *     and will be quoted appropriately. If NULL is inserted, this will be
 860          *     converted to a database NULL.
 861          *   - An array with numeric keys, holding a list of associative arrays.
 862          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
 863          *     each subarray must be identical to each other, and in the same order.
 864          *
 865          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
 866          * returns success.
 867          *
 868          * $options is an array of options, with boolean options encoded as values
 869          * with numeric keys, in the same style as $options in
 870          * IDatabase::select(). Supported options are:
 871          *
 872          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
 873          *     any rows which cause duplicate key errors are not inserted. It's
 874          *     possible to determine how many rows were successfully inserted using
 875          *     IDatabase::affectedRows().
 876          *
 877          * @param string $table Table name. This will be passed through
 878          *   DatabaseBase::tableName().
 879          * @param array $a Array of rows to insert
 880          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 881          * @param array $options Array of options
 882          *
 883          * @return bool
 884          */
 885         public function insert( $table, $a, $fname = __METHOD__, $options = [] );
 886
 887         /**
 888          * UPDATE wrapper. Takes a condition array and a SET array.
 889          *
 890          * @param string $table Name of the table to UPDATE. This will be passed through
 891          *   DatabaseBase::tableName().
 892          * @param array $values An array of values to SET. For each array element,
 893          *   the key gives the field name, and the value gives the data to set
 894          *   that field to. The data will be quoted by IDatabase::addQuotes().
 895          * @param array $conds An array of conditions (WHERE). See
 896          *   IDatabase::select() for the details of the format of condition
 897          *   arrays. Use '*' to update all rows.
 898          * @param string $fname The function name of the caller (from __METHOD__),
 899          *   for logging and profiling.
 900          * @param array $options An array of UPDATE options, can be:
 901          *   - IGNORE: Ignore unique key conflicts
 902          *   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 903          * @return bool
 904          */
 905         public function update( $table, $values, $conds, $fname = __METHOD__, $options = [] );
 906
 907         /**
 908          * Makes an encoded list of strings from an array
 909          *
 910          * These can be used to make conjunctions or disjunctions on SQL condition strings
 911          * derived from an array (see IDatabase::select() $conds documentation).
 912          *
 913          * Example usage:
 914          * @code
 915          *     $sql = $db->makeList( [
 916          *         'rev_user' => $id,
 917          *         $db->makeList( [ 'rev_minor' => 1, 'rev_len' < 500 ], $db::LIST_OR ] )
 918          *     ], $db::LIST_AND );
 919          * @endcode
 920          * This would set $sql to "rev_user = '$id' AND (rev_minor = '1' OR rev_len < '500')"
 921          *
 922          * @param array $a Containing the data
 923          * @param int $mode IDatabase class constant:
 924          *    - IDatabase::LIST_COMMA: Comma separated, no field names
 925          *    - IDatabase::LIST_AND:   ANDed WHERE clause (without the WHERE).
 926          *    - IDatabase::LIST_OR:    ORed WHERE clause (without the WHERE)
 927          *    - IDatabase::LIST_SET:   Comma separated with field names, like a SET clause
 928          *    - IDatabase::LIST_NAMES: Comma separated field names
 929          * @throws DBError
 930          * @return string
 931          */
 932         public function makeList( $a, $mode = self::LIST_COMMA );
 933
 934         /**
 935          * Build a partial where clause from a 2-d array such as used for LinkBatch.
 936          * The keys on each level may be either integers or strings.
 937          *
 938          * @param array $data Organized as 2-d
 939          *    [ baseKeyVal => [ subKeyVal => [ignored], ... ], ... ]
 940          * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
 941          * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
 942          * @return string|bool SQL fragment, or false if no items in array
 943          */
 944         public function makeWhereFrom2d( $data, $baseKey, $subKey );
 945
 946         /**
 947          * Return aggregated value alias
 948          *
 949          * @param array $valuedata
 950          * @param string $valuename
 951          *
 952          * @return string
 953          */
 954         public function aggregateValue( $valuedata, $valuename = 'value' );
 955
 956         /**
 957          * @param string $field
 958          * @return string
 959          */
 960         public function bitNot( $field );
 961
 962         /**
 963          * @param string $fieldLeft
 964          * @param string $fieldRight
 965          * @return string
 966          */
 967         public function bitAnd( $fieldLeft, $fieldRight );
 968
 969         /**
 970          * @param string $fieldLeft
 971          * @param string $fieldRight
 972          * @return string
 973          */
 974         public function bitOr( $fieldLeft, $fieldRight );
 975
 976         /**
 977          * Build a concatenation list to feed into a SQL query
 978          * @param array $stringList List of raw SQL expressions; caller is
 979          *   responsible for any quoting
 980          * @return string
 981          */
 982         public function buildConcat( $stringList );
 983
 984         /**
 985          * Build a GROUP_CONCAT or equivalent statement for a query.
 986          *
 987          * This is useful for combining a field for several rows into a single string.
 988          * NULL values will not appear in the output, duplicated values will appear,
 989          * and the resulting delimiter-separated values have no defined sort order.
 990          * Code using the results may need to use the PHP unique() or sort() methods.
 991          *
 992          * @param string $delim Glue to bind the results together
 993          * @param string|array $table Table name
 994          * @param string $field Field name
 995          * @param string|array $conds Conditions
 996          * @param string|array $join_conds Join conditions
 997          * @return string SQL text
 998          * @since 1.23
 999          */
1000         public function buildGroupConcatField(
1001                 $delim, $table, $field, $conds = '', $join_conds = []
1002         );
1003
1004         /**
1005          * @param string $field Field or column to cast
1006          * @return string
1007          * @since 1.28
1008          */
1009         public function buildStringCast( $field );
1010
1011         /**
1012          * Change the current database
1013          *
1014          * @param string $db
1015          * @return bool Success or failure
1016          */
1017         public function selectDB( $db );
1018
1019         /**
1020          * Get the current DB name
1021          * @return string
1022          */
1023         public function getDBname();
1024
1025         /**
1026          * Get the server hostname or IP address
1027          * @return string
1028          */
1029         public function getServer();
1030
1031         /**
1032          * Adds quotes and backslashes.
1033          *
1034          * @param string|int|null|bool|Blob $s
1035          * @return string|int
1036          */
1037         public function addQuotes( $s );
1038
1039         /**
1040          * LIKE statement wrapper, receives a variable-length argument list with
1041          * parts of pattern to match containing either string literals that will be
1042          * escaped or tokens returned by anyChar() or anyString(). Alternatively,
1043          * the function could be provided with an array of aforementioned
1044          * parameters.
1045          *
1046          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
1047          * a LIKE clause that searches for subpages of 'My page title'.
1048          * Alternatively:
1049          *   $pattern = [ 'My_page_title/', $dbr->anyString() ];
1050          *   $query .= $dbr->buildLike( $pattern );
1051          *
1052          * @since 1.16
1053          * @return string Fully built LIKE statement
1054          */
1055         public function buildLike();
1056
1057         /**
1058          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
1059          *
1060          * @return LikeMatch
1061          */
1062         public function anyChar();
1063
1064         /**
1065          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
1066          *
1067          * @return LikeMatch
1068          */
1069         public function anyString();
1070
1071         /**
1072          * Returns an appropriately quoted sequence value for inserting a new row.
1073          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
1074          * subclass will return an integer, and save the value for insertId()
1075          *
1076          * Any implementation of this function should *not* involve reusing
1077          * sequence numbers created for rolled-back transactions.
1078          * See http://bugs.mysql.com/bug.php?id=30767 for details.
1079          * @param string $seqName
1080          * @return null|int
1081          */
1082         public function nextSequenceValue( $seqName );
1083
1084         /**
1085          * REPLACE query wrapper.
1086          *
1087          * REPLACE is a very handy MySQL extension, which functions like an INSERT
1088          * except that when there is a duplicate key error, the old row is deleted
1089          * and the new row is inserted in its place.
1090          *
1091          * We simulate this with standard SQL with a DELETE followed by INSERT. To
1092          * perform the delete, we need to know what the unique indexes are so that
1093          * we know how to find the conflicting rows.
1094          *
1095          * It may be more efficient to leave off unique indexes which are unlikely
1096          * to collide. However if you do this, you run the risk of encountering
1097          * errors which wouldn't have occurred in MySQL.
1098          *
1099          * @param string $table The table to replace the row(s) in.
1100          * @param array $uniqueIndexes Is an array of indexes. Each element may be either
1101          *    a field name or an array of field names
1102          * @param array $rows Can be either a single row to insert, or multiple rows,
1103          *    in the same format as for IDatabase::insert()
1104          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1105          */
1106         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ );
1107
1108         /**
1109          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
1110          *
1111          * This updates any conflicting rows (according to the unique indexes) using
1112          * the provided SET clause and inserts any remaining (non-conflicted) rows.
1113          *
1114          * $rows may be either:
1115          *   - A single associative array. The array keys are the field names, and
1116          *     the values are the values to insert. The values are treated as data
1117          *     and will be quoted appropriately. If NULL is inserted, this will be
1118          *     converted to a database NULL.
1119          *   - An array with numeric keys, holding a list of associative arrays.
1120          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1121          *     each subarray must be identical to each other, and in the same order.
1122          *
1123          * It may be more efficient to leave off unique indexes which are unlikely
1124          * to collide. However if you do this, you run the risk of encountering
1125          * errors which wouldn't have occurred in MySQL.
1126          *
1127          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1128          * returns success.
1129          *
1130          * @since 1.22
1131          *
1132          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
1133          * @param array $rows A single row or list of rows to insert
1134          * @param array $uniqueIndexes List of single field names or field name tuples
1135          * @param array $set An array of values to SET. For each array element, the
1136          *   key gives the field name, and the value gives the data to set that
1137          *   field to. The data will be quoted by IDatabase::addQuotes().
1138          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1139          * @throws Exception
1140          * @return bool
1141          */
1142         public function upsert(
1143                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
1144         );
1145
1146         /**
1147          * DELETE where the condition is a join.
1148          *
1149          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
1150          * we use sub-selects
1151          *
1152          * For safety, an empty $conds will not delete everything. If you want to
1153          * delete all rows where the join condition matches, set $conds='*'.
1154          *
1155          * DO NOT put the join condition in $conds.
1156          *
1157          * @param string $delTable The table to delete from.
1158          * @param string $joinTable The other table.
1159          * @param string $delVar The variable to join on, in the first table.
1160          * @param string $joinVar The variable to join on, in the second table.
1161          * @param array $conds Condition array of field names mapped to variables,
1162          *   ANDed together in the WHERE clause
1163          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
1164          * @throws DBUnexpectedError
1165          */
1166         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
1167                 $fname = __METHOD__
1168         );
1169
1170         /**
1171          * DELETE query wrapper.
1172          *
1173          * @param array $table Table name
1174          * @param string|array $conds Array of conditions. See $conds in IDatabase::select()
1175          *   for the format. Use $conds == "*" to delete all rows
1176          * @param string $fname Name of the calling function
1177          * @throws DBUnexpectedError
1178          * @return bool|ResultWrapper
1179          */
1180         public function delete( $table, $conds, $fname = __METHOD__ );
1181
1182         /**
1183          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
1184          * into another table.
1185          *
1186          * @param string $destTable The table name to insert into
1187          * @param string|array $srcTable May be either a table name, or an array of table names
1188          *    to include in a join.
1189          *
1190          * @param array $varMap Must be an associative array of the form
1191          *    [ 'dest1' => 'source1', ... ]. Source items may be literals
1192          *    rather than field names, but strings should be quoted with
1193          *    IDatabase::addQuotes()
1194          *
1195          * @param array $conds Condition array. See $conds in IDatabase::select() for
1196          *    the details of the format of condition arrays. May be "*" to copy the
1197          *    whole table.
1198          *
1199          * @param string $fname The function name of the caller, from __METHOD__
1200          *
1201          * @param array $insertOptions Options for the INSERT part of the query, see
1202          *    IDatabase::insert() for details.
1203          * @param array $selectOptions Options for the SELECT part of the query, see
1204          *    IDatabase::select() for details.
1205          *
1206          * @return ResultWrapper
1207          */
1208         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
1209                 $fname = __METHOD__,
1210                 $insertOptions = [], $selectOptions = []
1211         );
1212
1213         /**
1214          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
1215          * within the UNION construct.
1216          * @return bool
1217          */
1218         public function unionSupportsOrderAndLimit();
1219
1220         /**
1221          * Construct a UNION query
1222          * This is used for providing overload point for other DB abstractions
1223          * not compatible with the MySQL syntax.
1224          * @param array $sqls SQL statements to combine
1225          * @param bool $all Use UNION ALL
1226          * @return string SQL fragment
1227          */
1228         public function unionQueries( $sqls, $all );
1229
1230         /**
1231          * Returns an SQL expression for a simple conditional. This doesn't need
1232          * to be overridden unless CASE isn't supported in your DBMS.
1233          *
1234          * @param string|array $cond SQL expression which will result in a boolean value
1235          * @param string $trueVal SQL expression to return if true
1236          * @param string $falseVal SQL expression to return if false
1237          * @return string SQL fragment
1238          */
1239         public function conditional( $cond, $trueVal, $falseVal );
1240
1241         /**
1242          * Returns a comand for str_replace function in SQL query.
1243          * Uses REPLACE() in MySQL
1244          *
1245          * @param string $orig Column to modify
1246          * @param string $old Column to seek
1247          * @param string $new Column to replace with
1248          *
1249          * @return string
1250          */
1251         public function strreplace( $orig, $old, $new );
1252
1253         /**
1254          * Determines how long the server has been up
1255          *
1256          * @return int
1257          */
1258         public function getServerUptime();
1259
1260         /**
1261          * Determines if the last failure was due to a deadlock
1262          *
1263          * @return bool
1264          */
1265         public function wasDeadlock();
1266
1267         /**
1268          * Determines if the last failure was due to a lock timeout
1269          *
1270          * @return bool
1271          */
1272         public function wasLockTimeout();
1273
1274         /**
1275          * Determines if the last query error was due to a dropped connection and should
1276          * be dealt with by pinging the connection and reissuing the query.
1277          *
1278          * @return bool
1279          */
1280         public function wasErrorReissuable();
1281
1282         /**
1283          * Determines if the last failure was due to the database being read-only.
1284          *
1285          * @return bool
1286          */
1287         public function wasReadOnlyError();
1288
1289         /**
1290          * Wait for the replica DB to catch up to a given master position
1291          *
1292          * @param DBMasterPos $pos
1293          * @param int $timeout The maximum number of seconds to wait for synchronisation
1294          * @return int|null Zero if the replica DB was past that position already,
1295          *   greater than zero if we waited for some period of time, less than
1296          *   zero if it timed out, and null on error
1297          */
1298         public function masterPosWait( DBMasterPos $pos, $timeout );
1299
1300         /**
1301          * Get the replication position of this replica DB
1302          *
1303          * @return DBMasterPos|bool False if this is not a replica DB.
1304          */
1305         public function getSlavePos();
1306
1307         /**
1308          * Get the position of this master
1309          *
1310          * @return DBMasterPos|bool False if this is not a master
1311          */
1312         public function getMasterPos();
1313
1314         /**
1315          * @return bool Whether the DB is marked as read-only server-side
1316          * @since 1.28
1317          */
1318         public function serverIsReadOnly();
1319
1320         /**
1321          * Run a callback as soon as the current transaction commits or rolls back.
1322          * An error is thrown if no transaction is pending. Queries in the function will run in
1323          * AUTO-COMMIT mode unless there are begin() calls. Callbacks must commit any transactions
1324          * that they begin.
1325          *
1326          * This is useful for combining cooperative locks and DB transactions.
1327          *
1328          * The callback takes one argument:
1329          *   - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)
1330          *
1331          * @param callable $callback
1332          * @param string $fname Caller name
1333          * @return mixed
1334          * @since 1.28
1335          */
1336         public function onTransactionResolution( callable $callback, $fname = __METHOD__ );
1337
1338         /**
1339          * Run a callback as soon as there is no transaction pending.
1340          * If there is a transaction and it is rolled back, then the callback is cancelled.
1341          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
1342          * Callbacks must commit any transactions that they begin.
1343          *
1344          * This is useful for updates to different systems or when separate transactions are needed.
1345          * For example, one might want to enqueue jobs into a system outside the database, but only
1346          * after the database is updated so that the jobs will see the data when they actually run.
1347          * It can also be used for updates that easily cause deadlocks if locks are held too long.
1348          *
1349          * Updates will execute in the order they were enqueued.
1350          *
1351          * The callback takes one argument:
1352          *   - How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)
1353          *
1354          * @param callable $callback
1355          * @param string $fname Caller name
1356          * @since 1.20
1357          */
1358         public function onTransactionIdle( callable $callback, $fname = __METHOD__ );
1359
1360         /**
1361          * Run a callback before the current transaction commits or now if there is none.
1362          * If there is a transaction and it is rolled back, then the callback is cancelled.
1363          * Callbacks must not start nor commit any transactions. If no transaction is active,
1364          * then a transaction will wrap the callback.
1365          *
1366          * This is useful for updates that easily cause deadlocks if locks are held too long
1367          * but where atomicity is strongly desired for these updates and some related updates.
1368          *
1369          * Updates will execute in the order they were enqueued.
1370          *
1371          * @param callable $callback
1372          * @param string $fname Caller name
1373          * @since 1.22
1374          */
1375         public function onTransactionPreCommitOrIdle( callable $callback, $fname = __METHOD__ );
1376
1377         /**
1378          * Run a callback each time any transaction commits or rolls back
1379          *
1380          * The callback takes two arguments:
1381          *   - IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK
1382          *   - This IDatabase object
1383          * Callbacks must commit any transactions that they begin.
1384          *
1385          * Registering a callback here will not affect writesOrCallbacks() pending
1386          *
1387          * @param string $name Callback name
1388          * @param callable|null $callback Use null to unset a listener
1389          * @return mixed
1390          * @since 1.28
1391          */
1392         public function setTransactionListener( $name, callable $callback = null );
1393
1394         /**
1395          * Begin an atomic section of statements
1396          *
1397          * If a transaction has been started already, just keep track of the given
1398          * section name to make sure the transaction is not committed pre-maturely.
1399          * This function can be used in layers (with sub-sections), so use a stack
1400          * to keep track of the different atomic sections. If there is no transaction,
1401          * start one implicitly.
1402          *
1403          * The goal of this function is to create an atomic section of SQL queries
1404          * without having to start a new transaction if it already exists.
1405          *
1406          * All atomic levels *must* be explicitly closed using IDatabase::endAtomic(),
1407          * and any database transactions cannot be began or committed until all atomic
1408          * levels are closed. There is no such thing as implicitly opening or closing
1409          * an atomic section.
1410          *
1411          * @since 1.23
1412          * @param string $fname
1413          * @throws DBError
1414          */
1415         public function startAtomic( $fname = __METHOD__ );
1416
1417         /**
1418          * Ends an atomic section of SQL statements
1419          *
1420          * Ends the next section of atomic SQL statements and commits the transaction
1421          * if necessary.
1422          *
1423          * @since 1.23
1424          * @see IDatabase::startAtomic
1425          * @param string $fname
1426          * @throws DBError
1427          */
1428         public function endAtomic( $fname = __METHOD__ );
1429
1430         /**
1431          * Run a callback to do an atomic set of updates for this database
1432          *
1433          * The $callback takes the following arguments:
1434          *   - This database object
1435          *   - The value of $fname
1436          *
1437          * If any exception occurs in the callback, then rollback() will be called and the error will
1438          * be re-thrown. It may also be that the rollback itself fails with an exception before then.
1439          * In any case, such errors are expected to terminate the request, without any outside caller
1440          * attempting to catch errors and commit anyway. Note that any rollback undoes all prior
1441          * atomic section and uncommitted updates, which trashes the current request, requiring an
1442          * error to be displayed.
1443          *
1444          * This can be an alternative to explicit startAtomic()/endAtomic() calls.
1445          *
1446          * @see DatabaseBase::startAtomic
1447          * @see DatabaseBase::endAtomic
1448          *
1449          * @param string $fname Caller name (usually __METHOD__)
1450          * @param callable $callback Callback that issues DB updates
1451          * @return mixed $res Result of the callback (since 1.28)
1452          * @throws DBError
1453          * @throws RuntimeException
1454          * @throws UnexpectedValueException
1455          * @since 1.27
1456          */
1457         public function doAtomicSection( $fname, callable $callback );
1458
1459         /**
1460          * Begin a transaction. If a transaction is already in progress,
1461          * that transaction will be committed before the new transaction is started.
1462          *
1463          * Only call this from code with outer transcation scope.
1464          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1465          * Nesting of transactions is not supported.
1466          *
1467          * Note that when the DBO_TRX flag is set (which is usually the case for web
1468          * requests, but not for maintenance scripts), any previous database query
1469          * will have started a transaction automatically.
1470          *
1471          * Nesting of transactions is not supported. Attempts to nest transactions
1472          * will cause a warning, unless the current transaction was started
1473          * automatically because of the DBO_TRX flag.
1474          *
1475          * @param string $fname Calling function name
1476          * @param string $mode A situationally valid IDatabase::TRANSACTION_* constant [optional]
1477          * @throws DBError
1478          */
1479         public function begin( $fname = __METHOD__, $mode = self::TRANSACTION_EXPLICIT );
1480
1481         /**
1482          * Commits a transaction previously started using begin().
1483          * If no transaction is in progress, a warning is issued.
1484          *
1485          * Only call this from code with outer transcation scope.
1486          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1487          * Nesting of transactions is not supported.
1488          *
1489          * @param string $fname
1490          * @param string $flush Flush flag, set to situationally valid IDatabase::FLUSHING_*
1491          *   constant to disable warnings about explicitly committing implicit transactions,
1492          *   or calling commit when no transaction is in progress.
1493          *
1494          *   This will trigger an exception if there is an ongoing explicit transaction.
1495          *
1496          *   Only set the flush flag if you are sure that these warnings are not applicable,
1497          *   and no explicit transactions are open.
1498          *
1499          * @throws DBUnexpectedError
1500          */
1501         public function commit( $fname = __METHOD__, $flush = '' );
1502
1503         /**
1504          * Rollback a transaction previously started using begin().
1505          * If no transaction is in progress, a warning is issued.
1506          *
1507          * Only call this from code with outer transcation scope.
1508          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1509          * Nesting of transactions is not supported. If a serious unexpected error occurs,
1510          * throwing an Exception is preferrable, using a pre-installed error handler to trigger
1511          * rollback (in any case, failure to issue COMMIT will cause rollback server-side).
1512          *
1513          * @param string $fname Calling function name
1514          * @param string $flush Flush flag, set to a situationally valid IDatabase::FLUSHING_*
1515          *   constant to disable warnings about calling rollback when no transaction is in
1516          *   progress. This will silently break any ongoing explicit transaction. Only set the
1517          *   flush flag if you are sure that it is safe to ignore these warnings in your context.
1518          * @throws DBUnexpectedError
1519          * @since 1.23 Added $flush parameter
1520          */
1521         public function rollback( $fname = __METHOD__, $flush = '' );
1522
1523         /**
1524          * Commit any transaction but error out if writes or callbacks are pending
1525          *
1526          * This is intended for clearing out REPEATABLE-READ snapshots so that callers can
1527          * see a new point-in-time of the database. This is useful when one of many transaction
1528          * rounds finished and significant time will pass in the script's lifetime. It is also
1529          * useful to call on a replica DB after waiting on replication to catch up to the master.
1530          *
1531          * @param string $fname Calling function name
1532          * @throws DBUnexpectedError
1533          * @since 1.28
1534          */
1535         public function flushSnapshot( $fname = __METHOD__ );
1536
1537         /**
1538          * List all tables on the database
1539          *
1540          * @param string $prefix Only show tables with this prefix, e.g. mw_
1541          * @param string $fname Calling function name
1542          * @throws DBError
1543          * @return array
1544          */
1545         public function listTables( $prefix = null, $fname = __METHOD__ );
1546
1547         /**
1548          * Convert a timestamp in one of the formats accepted by wfTimestamp()
1549          * to the format used for inserting into timestamp fields in this DBMS.
1550          *
1551          * The result is unquoted, and needs to be passed through addQuotes()
1552          * before it can be included in raw SQL.
1553          *
1554          * @param string|int $ts
1555          *
1556          * @return string
1557          */
1558         public function timestamp( $ts = 0 );
1559
1560         /**
1561          * Convert a timestamp in one of the formats accepted by wfTimestamp()
1562          * to the format used for inserting into timestamp fields in this DBMS. If
1563          * NULL is input, it is passed through, allowing NULL values to be inserted
1564          * into timestamp fields.
1565          *
1566          * The result is unquoted, and needs to be passed through addQuotes()
1567          * before it can be included in raw SQL.
1568          *
1569          * @param string|int $ts
1570          *
1571          * @return string
1572          */
1573         public function timestampOrNull( $ts = null );
1574
1575         /**
1576          * Ping the server and try to reconnect if it there is no connection
1577          *
1578          * @param float|null &$rtt Value to store the estimated RTT [optional]
1579          * @return bool Success or failure
1580          */
1581         public function ping( &$rtt = null );
1582
1583         /**
1584          * Get replica DB lag. Currently supported only by MySQL.
1585          *
1586          * Note that this function will generate a fatal error on many
1587          * installations. Most callers should use LoadBalancer::safeGetLag()
1588          * instead.
1589          *
1590          * @return int|bool Database replication lag in seconds or false on error
1591          */
1592         public function getLag();
1593
1594         /**
1595          * Get the replica DB lag when the current transaction started
1596          * or a general lag estimate if not transaction is active
1597          *
1598          * This is useful when transactions might use snapshot isolation
1599          * (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data
1600          * is this lag plus transaction duration. If they don't, it is still
1601          * safe to be pessimistic. In AUTO-COMMIT mode, this still gives an
1602          * indication of the staleness of subsequent reads.
1603          *
1604          * @return array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)
1605          * @since 1.27
1606          */
1607         public function getSessionLagStatus();
1608
1609         /**
1610          * Return the maximum number of items allowed in a list, or 0 for unlimited.
1611          *
1612          * @return int
1613          */
1614         public function maxListLen();
1615
1616         /**
1617          * Some DBMSs have a special format for inserting into blob fields, they
1618          * don't allow simple quoted strings to be inserted. To insert into such
1619          * a field, pass the data through this function before passing it to
1620          * IDatabase::insert().
1621          *
1622          * @param string $b
1623          * @return string
1624          */
1625         public function encodeBlob( $b );
1626
1627         /**
1628          * Some DBMSs return a special placeholder object representing blob fields
1629          * in result objects. Pass the object through this function to return the
1630          * original string.
1631          *
1632          * @param string|Blob $b
1633          * @return string
1634          */
1635         public function decodeBlob( $b );
1636
1637         /**
1638          * Override database's default behavior. $options include:
1639          *     'connTimeout' : Set the connection timeout value in seconds.
1640          *                     May be useful for very long batch queries such as
1641          *                     full-wiki dumps, where a single query reads out over
1642          *                     hours or days.
1643          *
1644          * @param array $options
1645          * @return void
1646          */
1647         public function setSessionOptions( array $options );
1648
1649         /**
1650          * Set variables to be used in sourceFile/sourceStream, in preference to the
1651          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
1652          * all. If it's set to false, $GLOBALS will be used.
1653          *
1654          * @param bool|array $vars Mapping variable name to value.
1655          */
1656         public function setSchemaVars( $vars );
1657
1658         /**
1659          * Check to see if a named lock is available (non-blocking)
1660          *
1661          * @param string $lockName Name of lock to poll
1662          * @param string $method Name of method calling us
1663          * @return bool
1664          * @since 1.20
1665          */
1666         public function lockIsFree( $lockName, $method );
1667
1668         /**
1669          * Acquire a named lock
1670          *
1671          * Named locks are not related to transactions
1672          *
1673          * @param string $lockName Name of lock to aquire
1674          * @param string $method Name of the calling method
1675          * @param int $timeout Acquisition timeout in seconds
1676          * @return bool
1677          */
1678         public function lock( $lockName, $method, $timeout = 5 );
1679
1680         /**
1681          * Release a lock
1682          *
1683          * Named locks are not related to transactions
1684          *
1685          * @param string $lockName Name of lock to release
1686          * @param string $method Name of the calling method
1687          *
1688          * @return int Returns 1 if the lock was released, 0 if the lock was not established
1689          * by this thread (in which case the lock is not released), and NULL if the named
1690          * lock did not exist
1691          */
1692         public function unlock( $lockName, $method );
1693
1694         /**
1695          * Acquire a named lock, flush any transaction, and return an RAII style unlocker object
1696          *
1697          * Only call this from outer transcation scope and when only one DB will be affected.
1698          * See https://www.mediawiki.org/wiki/Database_transactions for details.
1699          *
1700          * This is suitiable for transactions that need to be serialized using cooperative locks,
1701          * where each transaction can see each others' changes. Any transaction is flushed to clear
1702          * out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope,
1703          * the lock will be released unless a transaction is active. If one is active, then the lock
1704          * will be released when it either commits or rolls back.
1705          *
1706          * If the lock acquisition failed, then no transaction flush happens, and null is returned.
1707          *
1708          * @param string $lockKey Name of lock to release
1709          * @param string $fname Name of the calling method
1710          * @param int $timeout Acquisition timeout in seconds
1711          * @return ScopedCallback|null
1712          * @throws DBUnexpectedError
1713          * @since 1.27
1714          */
1715         public function getScopedLockAndFlush( $lockKey, $fname, $timeout );
1716
1717         /**
1718          * Check to see if a named lock used by lock() use blocking queues
1719          *
1720          * @return bool
1721          * @since 1.26
1722          */
1723         public function namedLocksEnqueue();
1724
1725         /**
1726          * Find out when 'infinity' is. Most DBMSes support this. This is a special
1727          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
1728          * because "i" sorts after all numbers.
1729          *
1730          * @return string
1731          */
1732         public function getInfinity();
1733
1734         /**
1735          * Encode an expiry time into the DBMS dependent format
1736          *
1737          * @param string $expiry Timestamp for expiry, or the 'infinity' string
1738          * @return string
1739          */
1740         public function encodeExpiry( $expiry );
1741
1742         /**
1743          * Decode an expiry time into a DBMS independent format
1744          *
1745          * @param string $expiry DB timestamp field value for expiry
1746          * @param int $format TS_* constant, defaults to TS_MW
1747          * @return string
1748          */
1749         public function decodeExpiry( $expiry, $format = TS_MW );
1750
1751         /**
1752          * Allow or deny "big selects" for this session only. This is done by setting
1753          * the sql_big_selects session variable.
1754          *
1755          * This is a MySQL-specific feature.
1756          *
1757          * @param bool|string $value True for allow, false for deny, or "default" to
1758          *   restore the initial value
1759          */
1760         public function setBigSelects( $value = true );
1761
1762         /**
1763          * @return bool Whether this DB is read-only
1764          * @since 1.27
1765          */
1766         public function isReadOnly();
1767
1768         /**
1769          * Make certain table names use their own database, schema, and table prefix
1770          * when passed into SQL queries pre-escaped and without a qualified database name
1771          *
1772          * For example, "user" can be converted to "myschema.mydbname.user" for convenience.
1773          * Appearances like `user`, somedb.user, somedb.someschema.user will used literally.
1774          *
1775          * Calling this twice will completely clear any old table aliases. Also, note that
1776          * callers are responsible for making sure the schemas and databases actually exist.
1777          *
1778          * @param array[] $aliases Map of (table => (dbname, schema, prefix) map)
1779          * @since 1.28
1780          */
1781         public function setTableAliases( array $aliases );
1782 }